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排序方式: 共有109条查询结果,搜索用时 15 毫秒
51.
52.
Erzsébet Varga Csenge Barabás Anita Tóth Imre Boldizsár Béla Noszál 《Natural product research》2019,33(11):1664-1669
Metabolite profile, antioxidant and antinociceptive activities of Syringa vulgaris bark and leaf methanolic extracts were investigated. By means of HPLC-DAD-ESI-TOF and HPLC-DAD-ESI-MS/MS, a total of 33 phenolics were identified, including 15 secoiridoids, 6 phenylpropanoids, 3 flavonoids, 3 lignans and 6 low molecular weight phenols. Validated quantitative analysis show that syringin (2.52%) and rutin (1.13%) are the main phenolic compounds in bark and leaf, respectively. Notable radical scavenging and antinociceptive activities of the bark and leaf extracts were confirmed by in vitro DPPH● and ABTS●+ assays and by in vivo hot-plate method in mice, respectively. Our results could lay the scientific basic of future clinical perspectives of lilac bark and leaf. 相似文献
53.
54.
Zoltán Aigner Erzsébet Szepesi Szilvia Berkó Csaba Novák Géza Regdon Jr. Mihály Kata 《Journal of inclusion phenomena and macrocyclic chemistry》2002,42(3-4):219-226
Cyclodextrin complexation was applied to achieve better aqueous solubility of the drug and to formulate suppositories. Binary products were prepared in several mole ratios by two different methods. The dissolution profiles and in vitro membrane diffusion behaviour of the compositions were investigated. Thermoanalytical studies were performed in order to confirm inclusion complex formation. Compositions were selected for further detailed investigations and for incorporation into suppository dosage form. 相似文献
55.
Frost RL Kristóf J Horváth E Kloprogge JT 《Journal of colloid and interface science》2001,239(1):126-133
Controlled rate thermal analysis (CRTA) technology made possible the separation of adsorbed formamide from intercalated formamide in formamide-intercalated kaolinites. X-ray diffraction shows that the CRTA-treated formamide-intercalated kaolinites remain expanded after CRTA treatment. The Raman spectra of the CRTA-treated formamide-intercalated kaolinites are significantly different from those of the intercalated kaolinites with both intercalated and adsorbed formamide. An intense band is observed at 3629 cm(-1), attributed to the inner surface hydroxyls hydrogen bonded to the formamide. Broad bands are observed at 3600 and 3639 cm(-1) and are attributed to the inner surface hydroxyls, which are hydrogen bonded to the adsorbed water molecules. The hydroxyl stretching band of the inner hydroxyl is readily observed at 3621 cm(-1) in the Raman spectra of the CRTA-treated formamide-intercalated kaolinites. The results of thermal analysis show that the amount of intercalated formamide between the kaolinite layers is independent of the presence of water. The Raman bands of the formamide in the CRTA-treated intercalated kaolinites are readily observed. Copyright 2001 Academic Press. 相似文献
56.
Photocatalytic degradation of 1,5-naphthalenedisulfonate on colloidal titanium dioxide 总被引:1,自引:0,他引:1
Szabó-Bárdos E Zsilák Z Lendvay G Horváth O Markovics O Hoffer A Töro N 《The journal of physical chemistry. B》2008,112(46):14500-14508
Photocatalytic degradation of 1,5-naphthalenedisulfonate (NDS) was investigated by monitoring the absorption and emission spectral changes, chemical oxygen demand, total organic carbon (TOC) content as well as pH and sulfate concentration. Intermediates formed during the irradiation were also detected by liquid chromatographic-mass spectrometric analysis. The results obtained by the applied analytical techniques clearly indicate that the initial step of degradation is oxygenation (hydroxylation) of the starting surfactant resulting in the formation of an 8-hydroxy derivative, although desulfonation and some mineralization, that is, decrease of TOC indicating carbon dioxide generation, also take place at this stage. Further oxygenation and desulfonation lead to the destruction of the diaromatic naphthalene system, then to ring fission, producing diols, aldehydes, and carboxylic acids on the side-chains. A tentative scheme involving possible pathways of degradation is proposed, taking the intermediates detected by mass spectrometry into consideration. On the basis of the results of quantum chemical calculations, the most possible points of attack by HO radical were identified, supplementing the MS results, and elucidating the initial oxidation step in the degradation of NDS and the benzenesulfonate (BS) intermediate. Thus, in the case of NDS para position is favored for hydroxylation, while for BS, formation of the ortho-hydroxy derivative is preferred. 相似文献
57.
Albert Lévai Gábor Tóth József Kovács Tamás Patonay Erzsébet B. Vass 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):707-713
Summary. Epoxidation of (Z)-3-arylidene-1-thioflavanones by sodium hypochlorite or alkaline hydrogen peroxide afforded diastereomeric mixtures of trans,cis- and trans,trans-epoxides. These were separated by silica gel column chromatography. Determination of the isomeric composition of the crude
reaction products and structure elucidation of all new isolated epoxides were performed by 1H and 13C NMR spectroscopy.
Received November 10, 2000. Accepted December 19, 2000 相似文献
58.
Perjési P Takács M Osz E Pintér Z Vámos J Takács-Novák K 《Journal of chromatographic science》2005,43(6):289-295
Some cyclic chalcone analogues [E-2-(X-benzylidene)-1-indanones, -tetralones, and -benzosuberones], on-plate UV light-catalyzed formation of new chromatographic spots, can be observed during thin-layer chromatography (TLC). Gas chromatographic (GC) analysis of selected derivatives indicates the formation of one new substance in each case. GC coupled with mass spectrometry and 1H NMR analysis of the samples reveals that the compounds formed are the respective Z-2-(X-benzylidene)-1-indanones, -tetralones, and -benzosuberones. Two-dimensional TLC shows that the E/Z isomerization is a reversible process. By means of the RP-TLC, the logarithm of n-octanol-water partition coefficient (log P) values of E- and Z-isomeric pairs of selected 2-(X-benzylidene)-1-benzosuberones is determined. The Z-isomers are less lipophilic than the E-isomers. 相似文献
59.
Erzsébet Néher-Neumann 《Journal of solution chemistry》2006,35(8):1109-1136
In the present part, potential functions are derived for the calculation of the total potential anomalies, Δ E B and Δ E H, for Emf cells where strong or weak complexes are formed, respectively. A weak or strong electrolyte is considered to be used as complexing agent (A y L), respectively, at the experimental condition, [Y?] = C mol?L?1, constant. The cells have indicator electrodes reversible to B z(B)+ (cell B) and H+ ions (cell H), respectively. The system, HY–BY z(B)-A Y L-AY and the protolysis of the acids HL and H2L in the ionic medium (A+, Y?) are studied. Here, y = |z L |. Moreover, some useful Emf titrations are suggested for the experimental determination of the slope functions SL(H, L?), SL (H, L2?) and SL(H, HL?). The usefulness of the derived potential functions is established using the H+-acetate? (CH3COO?) system as an example. 相似文献
60.
Erzsébet-Sára Bogya Réka Barabás Alexandra Csavdári Valentina Dejeu Ioan Bâldea 《Chemical Papers》2009,63(5):568-573
This paper aims to increase the sorption capacity of hydroxyapatite and to find the best apatite-based material for metal
ions sorption. The sorption process of copper ions from water solutions by HAP and structurally modified HAP was carried out
in this work. Structural modifications of HAP were realized in the preparation phase by an addition of sodium silica into
the reaction medium. The prepared materials were characterized by physical-chemical methods: IR, electron-microscopy and X-ray
diffraction. The composites characterized were tested in kinetic studies regarding ion exchange and adsorption of Cu2+. It was revealed that the silica content, particle size and initial copper ion concentration influence the process rate.
Presented at the 8th Conference on Solid State Chemistry, Bratislava, Slovakia, 6–11 July 2008. 相似文献